Date: Fri, 26 Jun 2015 18:00:29 +0000 (UTC) From: Tycho Nightingale <tychon@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r284877 - head/sys/amd64/vmm Message-ID: <201506261800.t5QI0TV2075956@svn.freebsd.org>
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Author: tychon Date: Fri Jun 26 18:00:29 2015 New Revision: 284877 URL: https://svnweb.freebsd.org/changeset/base/284877 Log: verify_gla() needs to account for non-zero segment base addresses. Reviewed by: neel Modified: head/sys/amd64/vmm/vmm_instruction_emul.c Modified: head/sys/amd64/vmm/vmm_instruction_emul.c ============================================================================== --- head/sys/amd64/vmm/vmm_instruction_emul.c Fri Jun 26 17:13:23 2015 (r284876) +++ head/sys/amd64/vmm/vmm_instruction_emul.c Fri Jun 26 18:00:29 2015 (r284877) @@ -2321,10 +2321,13 @@ decode_moffset(struct vie *vie) * page table fault matches with our instruction decoding. */ static int -verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie) +verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie, + enum vm_cpu_mode cpu_mode) { int error; - uint64_t base, idx, gla2; + uint64_t base, segbase, idx, gla2; + enum vm_reg_name seg; + struct seg_desc desc; /* Skip 'gla' verification */ if (gla == VIE_INVALID_GLA) @@ -2357,14 +2360,48 @@ verify_gla(struct vm *vm, int cpuid, uin } } - /* XXX assuming that the base address of the segment is 0 */ - gla2 = base + vie->scale * idx + vie->displacement; + /* + * From "Specifying a Segment Selector", Intel SDM, Vol 1 + * + * In 64-bit mode, segmentation is generally (but not + * completely) disabled. The exceptions are the FS and GS + * segments. + * + * In legacy IA-32 mode, when the ESP or EBP register is used + * as the base, the SS segment is the default segment. For + * other data references, except when relative to stack or + * string destination the DS segment is the default. These + * can be overridden to allow other segments to be accessed. + */ + if (vie->segment_override) + seg = vie->segment_register; + else if (vie->base_register == VM_REG_GUEST_RSP || + vie->base_register == VM_REG_GUEST_RBP) + seg = VM_REG_GUEST_SS; + else + seg = VM_REG_GUEST_DS; + if (cpu_mode == CPU_MODE_64BIT && seg != VM_REG_GUEST_FS && + seg != VM_REG_GUEST_GS) { + segbase = 0; + } else { + error = vm_get_seg_desc(vm, cpuid, seg, &desc); + if (error) { + printf("verify_gla: error %d getting segment" + " descriptor %d", error, + vie->segment_register); + return (-1); + } + segbase = desc.base; + } + + gla2 = segbase + base + vie->scale * idx + vie->displacement; gla2 &= size2mask[vie->addrsize]; if (gla != gla2) { - printf("verify_gla mismatch: " + printf("verify_gla mismatch: segbase(0x%0lx)" "base(0x%0lx), scale(%d), index(0x%0lx), " "disp(0x%0lx), gla(0x%0lx), gla2(0x%0lx)\n", - base, vie->scale, idx, vie->displacement, gla, gla2); + segbase, base, vie->scale, idx, vie->displacement, + gla, gla2); return (-1); } @@ -2398,7 +2435,7 @@ vmm_decode_instruction(struct vm *vm, in return (-1); if ((vie->op.op_flags & VIE_OP_F_NO_GLA_VERIFICATION) == 0) { - if (verify_gla(vm, cpuid, gla, vie)) + if (verify_gla(vm, cpuid, gla, vie, cpu_mode)) return (-1); }
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